Chemicals, fertilizers and other powdered or granulated substances are commonly applied to agricultural crops. Applicator implements for applying such substances commonly include a vehicle, usually self propelled, with a box and some type of distributing apparatus downstream from a box outlet. A spinner mechanism has been used for many years to simply throw the substances centrifugally outwardly from a location beneath the box outlet.
More recently, applicator implements for dry substances have used distributing apparatus with a pneumatic source for forcing the substance through a plurality of delivery channels spaced along the rear of the implement or along a boom supported by the implement. For example, U.S. Pat. No. 3,606,097 shows a blower for forcing conveyancing air through a distributing apparatus comprised of a plurality of channels leading to a fan like duct network. U.S. Pat. No. 3,926,377 shows a pair of fans which provide air to a centrifugal distributing device for conveyancing to a plurality of distribution tubes for output along arms extended from a vehicle.
Another exemplary implement is shown in U.S. patent application Ser. No. 288,675, filed July 31, 1981, which is assigned to the same assignee as the present application. The implement therein includes a blower for providing air generally downstream from the centrifugal distributing apparatus for pneumatically conveying the distributed substance through a plurality of tubes to outputs spaced along a boom.
None of the known devices includes mechanism for heating the conveyancing air. Although the latter implement operates well, substance could stick or be unevenly distributed if moisture is present. The implement includes a venturi restriction in the air system and it is known that air cools while going through the restriction, oftentimes causing condensation on surrounding parts. The present invention, therefore, is directed to using heated conveyancing air to reduce any condensation and eliminate or diminish the significance of other such problems, thereby providing dry conveyancing even in situations where such dry conveyancing performance may not otherwise be or have been possible.